Flammability of litter sampled according to two different methods: comparison of results in laboratory experiments

Ganteaume, Anne; Jappiot, Marielle; Curt, Thomas; Lampin, C.; Borgniet, L.

doi:10.1071/wf13045

Cited by 28 publications

(26 citation statements)

References 39 publications

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“…Although our study highlights trade‐offs among flammability attributes within grass and litter fuels, it is important to acknowledge that landscape flammability is far more complex than can be captured by a standardized sample of a single fuel type (Gill & Zylstra, ; de Magalhães & Schwilk, ; Varner et al ., ). There is a strong influence of packing and fuel arrangement on landscape flammability (de Magalhães & Schwilk, ; Ganteaume et al ., ). While it is difficult to envisage a particular fuel that is highly ignitable, combustible and sustainable, this might be possible for a landscape with a mix of fine and coarse fuels, suitably arranged to facilitate a ‘combustion cascade’, whereby the grass fuels are ignitable, litter fuels are combustible and coarse fuels sustain combustion over a long duration.…”

Section: Discussionmentioning

confidence: 97%

Does inherent flammability of grass and litter fuels contribute to continental patterns of landscape fire activity?

Prior

Murphy

Williamson

et al. 2016

Journal of Biogeography

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Aims To (1) identify the trade‐offs among flammability attributes within grass and litter fuel types; (2) determine how flammability attributes of grass and litter fuels vary across macro‐ecological gradients; and (3) test our hypothesis that inherent flammability attributes of grass and litter fuels scale to satellite‐derived proxies for fire frequency and intensity. Location Continent of Australia. Methods Samples of litter and grass fuels collected from 133 sites across Australia were oven dried, then burnt under controlled conditions. Measurements of ignitability, combustibility and sustainability were made. Estimates of fire frequency and fire radiative power (a proxy for intensity) were derived from satellite imagery. Multivariate analyses were used to identify inter‐relationships among variables and trends across macro‐ecological gradients. Results Flammability was best described by two axes: high rate of combustion versus long duration of burning, and fast rate of spread versus high maximum temperature. As expected, our study confirmed that grass and litter fuel types have inherently differently flammability attributes whereby grass samples burn more quickly, with a higher rate of spread, than litter samples. However, there were also smaller differences in flammability attributes within fuel types, which scaled to rainfall, temperature and soil phosphorus concentrations. In keeping with our hypothesis, we found correlations between inherent fuel flammability attributes and landscape fire activity across the Australian continent. Fire frequency and rate of combustion of grass fuels were both highest in the tropics, and fire intensity and maximum temperature during combustion of litter fuels were highest in temperate areas. Main conclusions At a continental scale, we found landscape fire activity was correlated with inherent flammability of grass and litter fuels. This inherent flammability contributes to observed pyrogeographical patterns that are shaped by climate through its known effects on plant productivity, the abundance of cured grass biomass and fire weather.

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Section: Discussionmentioning

confidence: 97%

Does inherent flammability of grass and litter fuels contribute to continental patterns of landscape fire activity?

Prior

Murphy

Williamson

et al. 2016

Journal of Biogeography

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“…; Ganteaume et al . ). Furthermore, a recent investigation of tropical rainforest‐savanna boundaries attributed the greater flammability of the savanna biome to the presence of low bulk density grass fuel, with lesser contributions from microclimatic variables (Hoffmann et al .…”

Section: Discussionmentioning

confidence: 97%

Vegetation, fire and soil feedbacks of dynamic boundaries between rainforest, savanna and grassland

et al. 2016

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At fine spatial scales, savanna-rainforest-grassland boundary dynamics are thought to be mediated by the interplay between fire, vegetation and soil feedbacks. These processes were investigated by quantifying tree species composition, the light environment, quantities and flammability of fuels, bark thickness, and soil conditions across stable and dynamic rainforest boundaries that adjoin grassland and eucalypt savanna in the highlands of the Bunya Mountains, southeast Queensland, Australia. The size class distribution of savanna and rainforest stems was indicative of the encroachment of rainforest species into savanna and grassland. Increasing dominance of rainforest trees corresponds to an increase in woody canopy cover, the dominance of litter fuels (woody debris and leaf), and decline in grass occurrence. There is marked difference in litter and grass fuel flammability and this result is largely an influence of strongly dissimilar fuel bulk densities. Relative bark thickness, a measure of stem fire resistance, was found to be generally greater in savanna species when compared to that of rainforest species, with notable exceptions being the conifers Araucaria bidwillii and Araucaria cunninghamii. A transect study of soil nutrients across one dynamic rainforestgrassland boundary indicated the mass of carbon and nitrogen, but not phosphorus, increased across the successional gradient. Soil carbon turnover time is shortest in stable rainforest, intermediate in dynamic rainforest and longest in grassland highlighting nutrient cycling differentiation. We conclude that the general absence of fire in the Bunya Mountains, due to a divergence from traditional Aboriginal burning practices, has allowed for the encroachment of fire-sensitive rainforest species into the flammable biomes of this landscape. Rainforest invasion is likely to have reduced fire risk via changes to fuel composition and microclimatic conditions, and this feedback will be reinforced by altered nutrient cycling. The mechanics of the feedbacks here identified are discussed in terms of landscape change theory.Austral Ecology (2017) 42, 154-164 Grassland invaded by young forest, typically including dense stands of Acacia and rain forest species but also minor areas of Eucalyptus spp. Woody cover is >30% Rainforest (stable rainforest)Closed forest without eucalypts in the canopy

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“…After the old leaves are shed, the probability of active crowning could decline (if the drop in canopy bulk density is high enough) and surface fires may become more likely and, potentially, more intense due to higher fuel load (note that the flammability of the surface fuel bed will also be affected by leaf traits that influence the packing and aeration of the fuel bed [Ganteaume et al. , Cornwell et al. ], but a full review of leaf traits and surface fuel is beyond the scope of this article).…”

Section: Fire Resistance At Individual Tree Levelmentioning

confidence: 99%

“…However, this effect is only transient and lasts for a few weeks, until leaf dropping. After the old leaves are shed, the probability of active crowning could decline (if the drop in canopy bulk density is high enough) and surface fires may become more likely and, potentially, more intense due to higher fuel load (note that the flammability of the surface fuel bed will also be affected by leaf traits that influence the packing and aeration of the fuel bed [Ganteaume et al 2014, but a full review of leaf traits and surface fuel is beyond the scope of this article). Such leaf senescence (that later leads to shedding in evergreens or drought deciduousness in deciduous species) may be adaptive for FIG.…”

Section: Structural Traitsmentioning

confidence: 99%

Fire‐induced deforestation in drought‐prone Mediterranean forests: drivers and unknowns from leaves to communities

Karavani

Boer

Baudena

et al. 2018

Ecological Monographs

113

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Over the past 15 years, 3 million hectares of forests have been converted into shrublands or grasslands in the Mediterranean countries of the European Union. Fire and drought are the main drivers underlying this deforestation. Here we present a conceptual framework for the process of fire‐induced deforestation based on the interactive effects of fire and drought across three hierarchical scales: resistance in individuals, resilience in populations, and transitions to a new state. At the individual plant level, we review the traits that confer structural and physiological resistance, as well as allow for resprouting capacity: deforestation can be initiated when established individuals succumb to fire. After individuals perish, the second step toward deforestation requires a limited resilience from the population, that is, a reduced ability of that species to regenerate after fire. If individuals die after fire and the population fails to recover, then a transition to a new state will occur. We document trade‐offs between drought survival and fire survival, as embolism resistance is negatively correlated with fire tolerance in conifers and leaf shedding or drought deciduousness, a process that decreases water consumption at the peak of the dry season, temporally increases crown flammability. Propagule availability and establishment control resilience after mortality, but different hypotheses make contrasting predictions on the drivers of post‐fire establishment. Mycorrhizae play an additional role in modulating the response by favoring recovery through amelioration of the nutritional and water status of resprouts and new germinants. So far, resprouter species such as oaks have provided a buffer against deforestation in forests dominated by obligate seeder trees, when present in high enough density in the understory. While diversifying stands with resprouters is often reported as advantageous for building resilience, important knowledge gaps exist on how floristic composition interacts with stand flammability and on the “resprouter exhaustion syndrome,” a condition where pre‐fire drought stress, or short fire return intervals, seriously restrict post‐fire resprouting. Additional attention should be paid to the onset of novel fire environments in previously fire‐free environments, such as high altitude forests, and management actions need to accommodate this complexity to sustain Mediterranean forests under a changing climate.

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Flammability of litter sampled according to two different methods: comparison of results in laboratory experiments

Cited by 28 publications

References 39 publications

Does inherent flammability of grass and litter fuels contribute to continental patterns of landscape fire activity?

Does inherent flammability of grass and litter fuels contribute to continental patterns of landscape fire activity?

Vegetation, fire and soil feedbacks of dynamic boundaries between rainforest, savanna and grassland

Fire‐induced deforestation in drought‐prone Mediterranean forests: drivers and unknowns from leaves to communities

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